In a general sense, the invention is directed to systems and methods for treating interior tissue regions of the body. More specifically, the invention is directed to systems and methods for treating dysfunction in body sphincters and adjoining tissue, e.g., in and around the lower esophageal sphincter and cardia of the stomach.
The gastrointestinal tract, also called the alimentary canal, is a long tube through which food is taken into the body and digested. The alimentary canal begins at the mouth, and includes the pharynx, esophagus, stomach, small and large intestines, and rectum. In human beings, this passage is about 30 feet (9 meters) long.
Small, ring-like muscles, called sphincters, surround portions of the alimentary canal. In a healthy person, these muscles contract or tighten in a coordinated fashion during eating and the ensuing digestive process, to temporarily close off one region of the alimentary canal from an other.
For example, a muscular ring called the lower esophageal sphincter surrounds the opening between the esophagus and the stomach. The lower esophageal sphincter (or LES) is a ring of increased thickness in the circular, smooth-muscle layer of the esophagus. Normally, the lower esophageal sphincter maintains a high-pressure zone between fifteen and thirty mm Hg above intragastric pressures inside the stomach.
When a person swallows food, muscles of the pharynx push the food into the esophagus. The muscles in the esophagus walls respond with a wavelike contraction called peristalsis. The lower esophageal sphincter relaxes before the esophagus contracts, and allows food to pass through to the stomach. After food passes into the stomach, the lower esophageal sphincter constricts to prevent the contents from regurgitating into the esophagus.
The stomach muscles churn the food and digestive juices into a mass called chyme. Then the muscles squeeze the chyme toward the pyloric (intestinal) end of the stomach by peristaltic waves, which start at the top of the stomach and move downward. The pyloric sphincter, another ringlike muscle, surrounds the duodenal opening. The pyloric sphincter keeps food in the stomach until it is a liquid. The pyloric sphincter then relaxes and lets some chyme pass into the duodenum.
Dysfunction of a sphincter in the body can lead to internal damage or disease, discomfort, or otherwise adversely affect the quality of life. For example, if the lower esophageal sphincter fails to function properly, stomach acid may rise back into the esophagus. Unlike the stomach, the esophagus has no natural protection against stomach acids. When the stomach contents make contact with the esophagus, heartburn or other disease symptoms, including damage to the esophagus, can occur.
Gastrointestinal reflux disease (GERD) is a common disorder, characterized by spontaneous relaxation of the lower esophageal sphincter. It has been estimated that approximately two percent of the adult population suffers from GERD. The incidence of GERD increases markedly after the age of 40, and it is not uncommon for patients experiencing symptoms to wait years before seeking medical treatment.
GERD is both a normal physiologic phenomenon that occurs in the general population and a pathophysiologic phenomenon that can result in mild to severe symptoms.
GERD is believed to be caused by a combination of conditions that increase the presence of acid ref lux in the esophagus. These conditions include transient LES relaxation, decreased LES resting tone, impaired esophageal clearance, delayed gastric emptying, decreased salivation, and impaired tissue resistance. Since the resting tone of the lower esophageal sphincter is maintained by both myogenic (muscular) and neurogenic (nerve) mechanisms, some believe that aberrant electrical signals in the lower esophageal sphincter or surrounding region of the stomach (called the cardia) can cause the sphincter to spontaneously relax.
Lifestyle factors can also cause increased risk of reflux. Smoking, large meals, fatty foods, caffeine, pregnancy, obesity, body position, drugs, hormones, and paraplegia may all exacerbate GERD. Also, hiatal hernia frequently accompanies severe GERD. The hernia may increase transient LES relaxation and delay acid clearance due to impaired esophageal emptying. Thus, hiatal hernias may contribute to prolonged acid exposure time following reflux, resulting in GERD symptoms and esophageal damage.
The excessive reflux experienced by patients with GERD overwhelms their intrinsic mucosal defense mechanisms, resulting in many symptoms. The most common symptom of GERD is heartburn. Besides the discomfort of heartburn, reflux results in symptoms of esophageal inflammation, such as odynophagia (pain on swallowing) and dysphagia (difficult swallowing). The acid reflux may also cause pulmonary symptoms such as coughing, wheezing, asthma, aspiration pneumonia, and interstitial fibrosis; oral symptoms such as tooth enamel decay, gingivitis, halitosis, and waterbrash; throat symptoms such as a soreness, laryngitis, hoarseness, and a globus sensation; and earache.
Complications of GERD include esophageal erosion, esophageal ulcer, and esophageal stricture; replacement of normal esophageal epithelium with abnormal (Barrett""s) epithelium; and pulmonary aspiration.
Treatment of GERD includes drug therapy to reduce or block stomach acid secretions. Still, daily drug therapy does not eliminate the root cause of the dysfunction.
Invasive abdominal surgical intervention has also been tried with success. One procedure, called Nissen fundoplication, entails invasive, open abdominal surgery. The surgeon wraps the gastric fundis about the lower esophagus, to, in effect, create a new xe2x80x9cvalve.xe2x80x9d Less invasive laparoscopic tehniques have also been tried to emulate Nissen fundoplication, also with success. Still, all surgical intervention entails making an incision into the abdomen and carry with it the usual risks of abdominal surgery.
One aspect of the invention provides cooled electrode assemblies for treating a tissue region at or near a sphincter. The assemblies actively cool mucosal surface tissue while applying energy through an electrode to ohmically heat tissue beneath the surface. The applied energy creates one or more lesions, or a prescribed pattern of lesions, below the mucosal surface. Natural healing of the subsurface lesions leads to a physical tightening of the sphincter and/or adjoining tissue to treat sphincter dysfunction. The active surface cooling preserves and protects the mucosal surface against thermal damage.
In one embodiment, an assembly for treating a tissue region at or near a sphincter comprises an electrode and a support structure including a spine that supports the electrode for contact with tissue. In this embodiment, the spine includes a cooling lumen attachable to a fluid source and an aspiration lumen attachable to an aspiration source. The cooling lumen has an outlet to dispense fluid into heat conductive contact with tissue in the tissue region. The aspiration lumen has an inlet to remove fluid from the tissue region.
In one embodiment, a fluid absorbing material overlays the outlet to retain fluid in heat conductive contact with tissue.
In one embodiment, the support structure includes an array of at least two spines having distal and proximal ends. Each spine includes an electrode support lumen for carrying an electrode, a cooling lumen attachable to a fluid source, and an aspiration lumen attachable to an aspiration source. In this embodiment, the cooling lumen has an outlet near the respective electrode to dispense fluid into heat conductive contact with tissue. The aspiration lumen has an inlet to remove fluid from the tissue region. In this embodiment, the inlet of one of the spines is located at or near the respective distal end, and the inlet of the other one of the spines being located at or near the respective proximal end.
In one embodiment, the support structure has an interior region for deployment in the tissue region. The support structure includes a spine extending outward of the interior region to support the electrode for contact with tissue. The spine includes a cooling lumen attachable to a fluid source, having an outlet to dispense fluid into heat conductive contact with tissue in the tissue region. In this embodiment, an aspiration lumen in the interior region is attachable to an aspiration source. The aspiration lumen has an inlet in the interior region to remove fluid from the tissue region.
In one embodiment, the aspiration lumen has inlets in the interior region located at or near the distal and proximal ends of the support structure.
In one embodiment, the aspiration lumen has an inlet that extends beyond the distal end of the support structure to remove fluid from the tissue region.
In one embodiment, an expandable balloon occupies an interior region of the support structure. The balloon includes a porous surface region adjacent the electrode. In this embodiment, an inflation lumen is located in the balloon attachable to a fluid source. The lumen has an outlet to dispense fluid into the balloon under pressure sufficient to expand the balloon and to also dispense fluid through the porous surface region into heat conductive contact with tissue in the tissue region.
Another aspect of the invention provides an electrode assembly for treating a tissue region at or near a sphincter, which delivers a therapeutic material to the tissue region independent of or as an adjunct to lesion formation. The assembly includes a support structure and an electrode carried by the support structure for advancement in a path to penetrate the tissue region. The electrode includes an interior lumen connectable to a source of a therapeutic material to convey the therapeutic material into contact with tissue in the tissue region. The therapeutic material can comprise, e.g., a tissue ablating chemical; or a drug, such as a tissue growth factor, or a fibrosis inducer, or a fibroblast growth factor, or a sclerosant; or a tissue bulking agent; or an exotoxin.
Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended claims.